Windows/Mac/Linux: Feed reader RSSOwl has long been a favourite of open-source advocates, despite being a bit less powerful than its competition. Version 2, however, brings OPML import/export, sharing and smart searching, finally giving it powers to rival its desktop counterparts.
If you were tempted by RSSOwl in the past, you may have been turned off by its inability to import feeds from other readers. Now, however, you can be set up and reading feeds exported from other readers within minutes. It also features a tabbed interface, so you don't have to constantly close feeds, and a built-in browser for you to view the full content of any article. In addition, you can do away with the usual 3-pane view and combine the rightmost two, viewing the entire feed's content in one pane, Google Reader style.
Possibly the coolest feature of RSSOwl, though, is searching. The app's got so many ways to search that it's a little overwhelming at first, but it's extremely powerful down the line. You can have multiple different conditions to any given search and save your searches — not unlike the "smart playlist" feature of media players — and group feeds by specific attributes. You can also use this as a filter, automatically filing incoming articles into news bins (akin to folders in an email client), marking them as sticky (akin to flagging or starring), or applying labels (akin to... labels) for super organisational powers.
There are too many features to describe in detail — other highlights include sharing via services including Facebook, Twitter, or Digg, and notifications (that integrate with Growl in OS X) — so check out their full overview for more detailed information. However, despite the power behind this app, it still seems to be missing integration with Google Reader, something we'd really like to see — but if you're not beholden to The Google for web-based RSS, this is definitely an app worth checking out.
RSSOwl is a free and open source download for all platforms. Thanks, Alin-Andrei!